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Resultados 851-860 de 1,956
Presence of plastic debris in loggerhead turtle stranded along the Tuscany coasts of the Pelagos Sanctuary for Mediterranean Marine Mammals (Italy) Texto completo
2013
This work evaluated the presence and the frequency of occurrence of marine litter in the gastrointestinal tract of 31 Caretta caretta found stranded or accidentally bycaught in the North Tyrrhenian Sea. Marine debris were present in 71% of specimens and were subdivided in different categories according to Fulmar Protocol (OSPAR 2008). The main type of marine debris found was user plastic, with the main occurrence of sheetlike user plastic. The small juveniles showed a mean±SD of marine debris items of 19.00±23.84, while the adult specimens showed higher values of marine litter if compared with the juveniles (26.87±35.85). The occurrence of marine debris observed in this work confirms the high impact of marine debris in the Mediterranean Sea in respect to other seas and oceans, and highlights the importance of Caretta caretta as good indicator for marine litter in the Marine Strategy Framework Directive (MSFD) of European Union.
Mostrar más [+] Menos [-]Inhibition of larval swimming activity of the coral (Platygyra acuta) by interactive thermal and chemical stresses Texto completo
2013
This study examined the interactive effects of copper and elevated temperature and subsequent depuration on Platygyra acuta coral larvae. Larval mortality and motility were significantly affected by copper alone (70% and 100% inhibition respectively). Their respective lethal/inhibitory concentration (LC50/IC50) were 10–130% and 86–193% higher than those reported for other larvae. Temperature (ambient, 27°C and elevated, 30°C) alone and the combination of temperature and copper did not significantly affect both endpoints. This study provides the first quantitative data on depuration effect on resumption of larval motility after copper exposure, although no sign of larval recovery was observed. These findings suggest that the effects of copper pollution outweigh the thermal tolerance of coral larvae. High LC50 and IC50 recorded may be unique for corals from marginal reefs like Hong Kong which have already been exposed to high levels of copper pollution.
Mostrar más [+] Menos [-]Temporal evolution of lead isotope ratios in sediments of the Central Portuguese Margin: A fingerprint of human activities Texto completo
2013
Stable Pb isotope ratios (206Pb/207Pb, 208Pb/206Pb), 210Pb, Pb, Al, Ca, Fe, Mn and Si concentrations were measured in 7 sediment cores from the west coast of the Iberian Peninsula to assess the Pb contamination throughout the last 200years. Independently of their locations, all cores are characterized by increasing Pb/Al rends not related to grain-size changes. Conversely, decreasing trends of 206Pb/207Pb were found towards the present. This tendency suggest a change in Pb sources reflecting an increased proportion derived from anthropogenic activities. The highest anthropogenic Pb inventories for sediments younger than 1950s were found in the two shallowest cores of Cascais and Lisboa submarine canyons, reflecting the proximity of the Tagus estuary. Lead isotope signatures also help demonstrate that sediments contaminated with Pb are not constrained to estuarine–coastal areas and upper parts of submarine canyons, but are also to transferred to a lesser extent to deeper parts of the Portuguese Margin.
Mostrar más [+] Menos [-]Marine dispersion assessment of 137Cs released from the Fukushima nuclear accident Texto completo
2013
Min, Byung-Il | Periáñez, Raúl | Kim, In-gyu | Suh, Kyung-Suk
Radionuclides were released into the atmosphere and ocean due to an accident in the Fukushima Daiichi Nuclear Power Plant (NPP) in March 2011. Numerical simulations were carried out to evaluate the distribution of 137Cs in the ocean considering both direct releases to the sea and deposition from the atmosphere as source terms. A significant amount of atmospheric deposition occurred on the sea surface in the northeast direction from the Fukushima NPP, due to westerly winds and precipitations on March 15–31, 2011. In a previous study using local scale modeling, no significant differences in resulting 137Cs patterns in water and sediments with and without atmospheric deposition were found. However, this new research, on a regional scale, has pointed out meaningful differences in seabed sediment radionuclide concentrations in the Fukushima northeast area with and without atmospheric deposition.
Mostrar más [+] Menos [-]Morphological changes in branchial mitochondria-rich cells of the teleost Paralichthys olivaceus as a potential indicator of CO2 impacts Texto completo
2013
We studied the morphological and biochemical changes of mitochondria-rich cells (MRCs) of a demersal teleost, Paralichthys olivaceus, during exposure to 0.98, 2.97 and 4.95kPa pCO2. The apical opening area of MRCs increased 2.2 and 4.1 times by 24h exposure to 2.97 and 4.95kPa pCO2, respectively, while the cross-sectional area or density of MRCs did not change. Gill Na+/K+-ATPase activity more than doubled at 72h and then returned to the pre-exposure level at 168h in 0.98kPa pCO2, while it increased 1.7 times at 24h at 4.95kPa. These results indicate that the apical opening area of MRCs and the gill Na+/K+-ATPase activity may be used as an indicator of acute (up to 72h), but not chronic, impacts of high (>1kPa) seawater CO2 conditions in P. olivacues. Limitations of those parameters as indices of CO2 impacts are discussed.
Mostrar más [+] Menos [-]Biogeochemical classification of South Florida’s estuarine and coastal waters Texto completo
2013
Briceño, Henry O. | Boyer, Joseph N. | Castro, Joffre | Harlem, Peter
South Florida’s watersheds have endured a century of urban and agricultural development and disruption of their hydrology. Spatial characterization of South Florida’s estuarine and coastal waters is important to Everglades’ restoration programs. We applied Factor Analysis and Hierarchical Clustering of water quality data in tandem to characterize and spatially subdivide South Florida’s coastal and estuarine waters. Segmentation rendered forty-four biogeochemically distinct water bodies whose spatial distribution is closely linked to geomorphology, circulation, benthic community pattern, and to water management. This segmentation has been adopted with minor changes by federal and state environmental agencies to derive numeric nutrient criteria.
Mostrar más [+] Menos [-]Developing human capital for successful implementation of international marine scientific research projects Texto completo
2013
Morrison, R.J. | Zhang, J. | Urban, E.R. | Hall, J. | Ittekkot, V. | Avril, B. | Hu, L. | Hong, G.H. | Kidwai, S. | Lange, C.B. | Lobanov, V. | Machiwa, J. | San Diego-McGlone, M.L. | Oguz, T. | Plumley, F.G. | Yeemin, T. | Zhu, W. | Zuo, F.
The oceans play a crucial role in the global environment and the sustainability of human populations, because of their involvement in climate regulation and provision of living and non-living resources to humans. Maintenance of healthy oceans in an era of increasing human pressure requires a high-level understanding of the processes occurring in the marine environment and the impacts of anthropogenic activities. Effective protection and sustainable resource management must be based, in part, on knowledge derived from successful research. Current marine research activities are being limited by a need for high-quality researchers capable of addressing critical issues in broad multidisciplinary research activities. This is particularly true for developing countries which will require the building of capacity for marine scientific research. This paper reviews the current activities aimed at increasing marine research capacity in developing and emerging countries and analyses the challenges faced, including: appropriate alignment of the research goals and societal and policy-relevant needs; training in multidisciplinary research; increasing capacity for overall synthesis of scientific data; building the capacity of technical staff; keeping highly qualified personnel in marine scientific research roles; cross-cultural issues in training; minimising duplication in training activities; improving linkages among human capital, project resources and infrastructure. Potential solutions to these challenges are provided, along with some priorities for action aimed at improving the overall research effort.
Mostrar más [+] Menos [-]Different chemical properties of lead in atmospheric particles from urban roadside and residential areas Texto completo
2013
Funasaka, Kunihiro | Tojo, Toshiki | Kaneco, Satoshi | Takaoka, Masaki
Lead in atmospheric suspended particles was fractionized using simple acid extraction to assess differences in chemical properties of lead from roadside and residential areas. The Pb–LIII edge XANES measurement was also challenged to explore the possibilities of contamination from road dust into the air. Results suggest that 0.1 M–HCl extractable fractions of lead at the roadside area are significantly higher than those obtained at the residential area, especially for the coarse mode of the particulate samples. Moreover, the solubility characteristics of the roadside particulate lead have partially overlapped with those of the road dust samples. The XANES spectra for coarse mode of particulate lead also nearly correspond to that of the road dust collected around the roadside area. These results indicate effects by the re–suspension of road dust to the roadside air. However, it is difficult to clear the roadside contamination from specific lead material applied in this study. This might suggest that specific lead compounds do not exist exclusively in atmospheric particles but exist as mixtures or unknown complexes.
Mostrar más [+] Menos [-]Impacts of long-line aquaculture of Pacific oysters (Crassostrea gigas) on sulfate reduction and diffusive nutrient flux in the coastal sediments of Jinhae–Tongyeong, Korea Texto completo
2013
Hyun, Jung-Ho | Kim, Sŭng-han | Mok, Jin-Sook | Lee, Jae-seong | An, Sung-Uk | Lee, Won-Chan | Jung, Rae-Hong
We investigated the environmental impacts of long-line aquaculture of Pacific oysters (Crassostrea gigas) on sediment geochemistry and carbon oxidation by sulfate reduction and diffusive benthic nutrient flux in a coastal ecosystem in Korea. Inventories of the NH4+ and HPO42- at the farm site were 7.7–11.5 and 1.8–8.0 times higher, respectively, than those at a reference site. Sulfate reduction rates (SRRs) at the oyster farm were 2.4–5.2 times higher than SRRs at the reference site. The SRRs at the farm site were responsible for 48–99% (average 70%) of the total C oxidation in the sediment. The diffusive benthic fluxes of NH4+ and HPO42- at the oyster farm were comparable to 30–164% and 19–58%, respectively, of the N and P demands for primary production, and were responsible for the enhanced benthic microalgal biomass on the surface sediment.
Mostrar más [+] Menos [-]Concentration and composition of polycyclic aromatic hydrocarbons (PAHs) in plastic pellets: Implications for small-scale diagnostic and environmental monitoring Texto completo
2013
Fisner, Mara | Taniguchi, Satie | Majer, Alessandra P. | Bícego, Márcia C. | Turra, Alexander
Plastic pellets may serve as a carrier of toxic contaminants, including polycyclic aromatic hydrocarbons (PAHs). Considering that beach morphodynamics and pellet distribution varied along the shore, and that contaminant sources may vary on different scales, it is expected that this variability is reflected in the concentration and composition of contaminants. This hypothesis was tested through a sampling of plastic pellets at 30 sites along the shore in Santos Bay (Brazil). The total PAH concentrations and the priority PAHs showed high variability, with no clear pattern. Their composition differed among the sampling sites; some of the compounds represent a potential risk to organisms. The sources of contamination, as indicated by the isomer ratios, were also variable among sites. The high small-scale spatial variability found here has implications for estimating the plastic pellet contamination on beaches, since a sample from a single site is unlikely to be representative of an entire beach.
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